1. The degree ratio of the three internal angles of the triangle is 2: 3: 4. What is the biggest angle in this triangle?

180(2+3+4)×4 = 80 (degrees)

2. After a construction site used 30% cement, it shipped 10 ton, and the total cement at this time was just 3/4 of the original. How many tons of raw cement are there in this site?

After using up 30%, the rest

1-30%=70%

Then 10 ton is the original.

3-70%=5%

There was one at first.

10÷5%=200 (ton)

3. Congcong's family and Mingming's family share a faucet. There are four people in Congcong's family and five people in Mingming's family. Last month, the two households used 0/0/0.8 tons of water. According to the charge of 2.35 yuan per ton of water, how much water fee should each family share?

The total water fee is

2.35× 10.8=25.38 (yuan)

per capita

25.38(4+5)= 2.82 yuan.

Congcongjia stock

2.82×4= 1 1.28 (yuan)

Mingmingjia stock

2.82×5= 14. 1 (yuan)